A suspension apparatus for an automotive vehicle not only supports a weight of the vehicle (a sprung weight), but also mitigates vibrations due to roughness of a road surface for improving ride comfort of the vehicle and reduces dynamic load that is applied to various portions of a body of the vehicle for improving running stability of the vehicle. One of elements that constitute the suspension apparatus is a shock absorber, and there has been developed, as the shock absorber, an electromagnetic absorber operable to generate, based on a force of a motor, a damping force with respect to a relative movement of a sprung portion and an unsprung portion of the vehicle.
The above-described electromagnetic absorber is operable to generate the damping force by shortcircuiting a coil of the motor, in other words, by electrically connecting terminals of the motor outside the motor. For instance, Japanese Patent Application Publication JP-A-2003-223220 describes an electromagnetic suspension apparatus in which a damping force is generated by shortcircuiting the coil of the motor when the electromagnetic suspension apparatus is out of control. Japanese Patent Application Publication JP-A-2001-310736 discloses a technique of controlling the damping force in relation to a control for an electromagnetic suspension apparatus. More specifically, in the disclosed technique, two of four coils of respective four electromagnetic absorbers are connected, and directions of respective current flows in the respective two coils are changed depending upon changes in the posture of the vehicle, thereby controlling directions of respective electromagnetic forces to be generated. Thus, the damping force is controlled.